Hi Folks! Anybody know where http://ledcalc.com/#calc website has gone? This was the best place for calculating resistor values for LED's in my opinion. Unfortunately, it won't come up when I put in the URL. Any ideas? Thanks.
Brian
Oh, come on. It's a simple math problem. Open a spreadsheet and put a few formulas in some cells...
LED(resistor) ≈ (Vcc - 2v ) ÷ LED(current)
Or,
LED(resistor) ≈ (Vcc - Vf) ÷ LED(current)
where Vf = the LED forward voltage
Calculate in your head. 50 ohms per volt of drop for 20mA (typical LED If). Say 1.8V red LED on 5v supply. Drop = 5 - 1.8 or 3.2V. Times 50 ohms/volt, gives 160 ohms.
High efficiency blue LED with 4.5 Vf running at 10 mA from 12V. 10mA is 100 ohms/volt. Drop is 12 - 4.5 or 7.5V, times 100 ohms/volt is 750 ohms.